1. Field of the Invention
The present invention relates to a shift-by-wire device and a transmission device mounting thereon the same, and more particular, to a shift-by-wire device connected communicatively to an administrative electronic control unit, which inputs thereinto a signal from a shift position sensor for detection of a demanded shift position demanded by a driver, to drivingly control a manual shaft on the basis of a shift command from the administrative electronic control unit to actuate an object being actuated, an automatic transmission, and a transmission device mounting thereon the shift-by-wire device.
2. Description of the Related Art
Conventionally, there has been proposed, as a transmission device of this type, one mounted on a vehicle and comprising a shift-by-wire system including two by-wire ECUs that drivingly controls a manual valve of a hydraulic circuit, and an automatic transmission control system including an automatic transmission ECU (see, for example, JP-A-2006-335157 (Patent Document 1)). With the device, the shift-by-wire system is provided with two drive units that individually generate torque on an electric motor for driving of the manual valve, the two by-wire ECUs are connected electrically to each other through the two drive units and a switching device, the automatic transmission control system monitors the two by-wire ECUs of the shift-by-wire system, and abnormality in the by-wire ECUs is coped with by switching the switching device so that when abnormality occurs in one of the two by-wire ECUs, the manual valve is drivingly controlled by the other of the two by-wire ECUs, which is normal.
With the transmission device, while the other of the two by-wire ECUs, which is normal, can drivingly control the manual valve even when abnormality occurs in one of the two by-wire ECUs, the device is made large in size and complex because of the need of arranging a surplus ECU, which is used only at the time of abnormality and providing the switching device that switches the driving ECU out of the two by-wire ECUs. In particular, the problem described above becomes further conspicuous since a transmission device is limited in a space for arrangement of an ECU by virtue of being mounted on a vehicle.